Method of working upon surfaces of ebonite articles



Patented S ept. 21,1926.

UNITED STATES nYosiIxE Narnia, or xImroYosnIma-GUN, JAPAN.

narnon or won'xme uron sunracns or nnomrn nnrrcnas.

80 Drawing.

. My invention relates .to methods of working uponsurfaces of articles of ebonite or equivalent. material, and particularly to methods for producing patterns or figures I upon surfaces of said articles.

I An object of my invention is to obtain ,ebonite articles the surfaces of which are positively kept of deep black colour without any of the appreciable fading which is 10 usual for ordinary ebonite articles.

Another object of my invention is to obtain ebonite articles having surfaces on which any desired patterns or figures are to provide a method for converting'the skinportion of ebonite rticles into another substance which-isdifierent from ebonite both 2 in quality and nature. As to articles made of ebonite, such as-for fountain-pen barrels or casings, or electrical insulators, it has long been complained that the surface or skin portions can not be an durable against the external air which causes colour fading'and insulation defects, and patterns or figures formed thereon'have a tendency of gradual disappearance, not by reason of wearing.

' 86 As is well known, ebonite is a substance 7 produced by mixing and grinding together rubber and sulphur, and heating the same.

It has 'a tendency of absorbing moisture in .the external air, and consequently its elec- 40 'trical insulating power is gradually depreciated. Moreover, the humidity absorbed in skin portions of ebonite articles effloresce the latter by aid. of external light or heat, and thereby the r0 er deep black colour of ebonite 'gradua y ades in a relatively short course of time, resulting in a W brownish black.

According to my experiments, it has been found impossible to. get rid of such numerous ebonite proper is protectedby a substantial and strong covering offpermanent tightness from theencroaching o moisture in the air. 'On the other hand, for putting patterns or before the ebonite undesirable effects of the air, unless .the

Application filed April 14, 1925. Serial No. 23,167.

figures on ebonite surfaces, it is the Well GI known art to apply moulds on the surface, as become rigid and the desired patterns or figures are impressed thereon. After it has been cooled, the impressed patterns or figures are kept in shape under a certain degree of mechanical stress. It W111 be then a natural result that the impressed portion of ebonite has a tendency to recover lts initial shape or form. and th1s tendency is present on every, occasion when the ebonite articles are subjected to some degree of heating, even by the heat of the human hand grasping it, or by-absorption of sun lights. The patterns or figures then gradually dlsappear automatically and not by reason of wearing.

-According to my invention, I convert skin portions of ebonite into another substance different from ebonite proper both in nature and composition, which substance is (I known as flaccanite. The lacconite is substantial, strong and hard in nature, and extremely durable against efliorescence,

Many attempts have already been made to cover ebonite surfaces with another material, but partly due to the covering material selected and partly due to im roper method of applying the same, such asby mere paintng, none of them has shown any successful result. i 1 Acoording to my invention, I use a varmsh WhlOh was formerly peculiar to Japan and known as japan lacquer.

The varnish or japan lacquer is made from the juice of a tree known in Japan as the urushi tree. Its composition is not qulte definite but varies .aiccordin to the -soil and climate, a's we'll as metho "of cultivation and other conditions.

Analyt cal examination of three typical examples give the followingresults:

SampleI Sample II Sample!!! 10.04 g 17. was; #1. ans a me 1.

m -i UrHLol (umshic or Japanic 1m Prs sane

lUrushiol or japanic acid is an inorganic acid proper to japan lacquer and contains tannic acid. 4

An ebonite article .to be worked on' is,

whilst ina cold condition, rotated about its axis, or reciprocated in'a plane, at a considerable' high speed. These movements may be effected by any suitable means. To 5 the moving surface of the ebonite article there is applied a piece of felt having the varnish or japan lacquer adhered thereto, and which felt is applied to the article with a certain amount of pressure. As the movement proceeds the varnish is gradually forced into the surface portion of ebonite, or in other words, the surface portion is impregnated with the varnish. The impregnation isfacilitated by the heat generated by friction of the felt.

fB the above process, the surface portion 0 which is substantial, strong and hard in nature and non-hygroscopic and durable against the air.

It is assumed that during such treatment, free sulphur contained in the rubber andan acid proper to the varnish, forms a kind of sulphide called laccanite which has the nature above disclosed. It is not, however,

\my intention to place any limitation on my invention by way of the above theory.

.For the sake of convenience, the above process or treatment is referred to as the laccanite process in the present description.

To facilitate the laccanite process, there may be initially mixed with the ebonite material a small amount of ferrous sulphide and japan lacquer. With this modification, the ferrous sulphide, together with'tannic acid contained by the japanic acid in the japan lacquer, results in a skin part of a deep black colour, and on theother hand 40 the japan lacquer within .the ebonite combines with the japan lacquer applied threto I through the laccanite process, resulting in a strong and hard covering on the ebonite proper.

For finishing additional coats of the var- Dish on the skin may be applied. The painted japan lacquer firmly combines with the free japan lacquer within the laccaniteskin and constitutes a second layer of cover- %or. articles, on the surfaces of which patterns or figures are to be produced, the above process can not be directly applied. In this case, the ebonite article to be worked onis first prepared through' the usual process or. patterning, that is to say 'its'surface-is marked with a pattern or figure which is a negative of the desiredpattern, by means 6 of a pressing mould before it has been process as previously 0 ebonite is'converted into a substance cooled. The article is then cooled 'and sub- I laccanite as the surface portion is uniformly subjected to the laccamte process, irrespective of the concave and convex portions of the negative pattern, In other words, the concave parts of the pattern are filled up by laccanite and the convex parts are covered by a thinner layer of laccanite than for the formers. The article is then dryed surface or the layer of laccanite projects at the parts corresponding to the said concave portlons, thus producing upon the surface the desired pattern or figure.

The resulting pattern or figure is formed by the laccanite only which covers the ebonits proper, and consequently is strong and hard, durable against any humidity and heating, and has not-the tendency to gradually disappear, as in ordinary ebonite, except by wear.

Though I have described my invention in respect of ebonite, it will readily be understood by those skilled in the art that my invention is not restricted to ebonite only but to be applicable with similar results on any other substance of like nature such as insulating compound or other vulcanized rubber compositions, or' phenol condensation products.

Having now particularly described and ascertained the nature of my invention and in what manner the same is to be performed, I declare that what I- claim is:' q i 1. In a method for patterning or figuring on the surface of ebonite or like substance, comprising producing a negativeipattern or figure on the surface of said'substance by pressing at its soft condition, cooling the same to rigidness, forcing japan lacquer into the skin portion thereof until to get a. substantially continuous surface, subjecting the same to a heating,and then cooling the same. s

2. In a method for converting the skin portion of ebonite or like substance into quite a different substance, comprising initially adding an amount of ferrous sulphide and japan lacquer to said substance before vulcanization thereof, cooling 'the same to rigidness, and forcing japan lacquer into the skin portion-thereof. v

.3. In a method for patterning on the surface of an ebonite rod, consisting of producing a negative pattern on the surface. of said rod by pressing at its soft condition, cooling the sameto rigidness, subjectin it to arotating movement about its longitudinal 130 axis, applying under pressure a felt piece face of ebonite or like substance, consisting 7 having an amount of japan lac uer adhered in forcing japan lacquer into the skin por thereto upon the surface of said rod, finishtion of sand substance. 10 ing the surface, subjecting the rod to a heat- In testimony whereof I affix my signa- 5 ing at a temperature of 70 C. to 80 C., turc.

and then cooling the same. Y

4. In a method of working upon the sur- RYOSUKE NAMIKI. 

